targetissleeping -- because Assassination would love this. targetisparalyzed targetisunaware secondarystatrequirement (requiring id="X" and secondarystatamount="Y") primarystatrequirement (ditto) weaponclass (requiring type="X", where X is the weapon type number from itemDB.xml) That's just offhand -- feel free to post and add more!
targetisfeared ..isconfused ..isrooted ..ispeaceful (most of the time this means they're pacified) casterisstealthed targetcanseecaster (ie within the sight cone) and then some way to invert these. Notconditions="1" or something.
Unless there's some way to do this already, I'd like a requirebuffontargettrigger or something similar for a skill I started on before I realized requirebuffontrigger didn't work the way I thought it did.